Project Background: Medication reconciliation, a process by which a provider obtains and documents a thorough medication history with specific attention to comparing current and previous medication use, can prevent medication-related errors and harm. The most important information-related barrier to effective medication reconciliation is the unreliability of patients' own reports about their medication use and incomplete provider history-taking. The James J. Peters VA (JJP VA) is an original participating facility in the Bronx RHIO, a New York State-funded health information exchange organization that in October 2008 implemented secure clinical data information exchange among the largest healthcare providers in the Bronx. JJP VA providers can now access key clinical data, including medication use, from non-VA facilities with patients' consent. This presents a research opportunity to develop a medication review process that takes advantage of real-time non-VA medication use data to reduce adverse drug events in veterans. It also provides an opportunity to examine implementation factors regarding incorporating RHIO access into everyday workflow for VA providers. We posit that routine access to medication information from outside the VA has the potential to prevent harmful drug discrepancies and combinations, to prevent adverse drug events (ADEs), and reduce inpatient costs in veterans. Project Objectives: 1) To adapt a medication reconciliation process to include information from a regional health information exchange (RHIO), 2) To conduct a controlled trial of a medication reconciliation process at the time of hospital admission either enhanced or not enhanced with data from a regional health information exchange, and examine effects on transition drug risk, adverse drug events, and total inpatient costs, and 3) To identify system and provider factors that impede and facilitate adoption of the information exchange tool for routine use by VA providers. Project Methods: We will conduct qualitative and quantitative studies. First we will perform cognitive task analysis (CTA) to examine providers' decision-making and to map RHIO tool functions while providers interface with the tool, with interview questions to identify factors that facilitate or hinder use. Second we will enroll patients admitted to 2 inpatient units at the JJP VA, and assign them to receive usual medication reconciliation or RHIO-enhanced medication reconciliation with a notification to physicians about the patient's non-VA services that can be viewed in the RHIO. We will measure transition drug risk and ADEs by medical record review and patient interview, and measure inpatient costs with administrative cost data from national VA datasets. Third, we will conduct CTA with pharmacists and physicians at the end of the quantitative study who are expert in use of the tool to characterize differences in cognitive processes from prior to the quantitative study. This will supply information on system and provider factors that impede and facilitate adoption of the tool for routine use, and on potential improvements in the tool.